Reduction of the Secondary Losses In Compressor Cascades – Numerical Simulation
R. Müller, K. Vogeler
Recent experimental investigations have shown a possible reduction of secondary losses in compressor cascades using a bulb like modification of the profile at the endwall. This paper is focussed on numerical work in comparison of 2 modifications at a compressor cascade. The cascade is modified near the endwall using a bulb.
The investigations have been carried out on a profile developed from a hub section of the Dresden Low Speed Research Compressor (LSRC) rotor blade, a compressor profile with a nominal turning of 18 degree.
A datum and a bulb configuration were simulated using the DLR code TRACE. An intensified horse shoe vortex was suspected and observed counterrotating to the passage vortex with an influence on its propagation. This proves the authors physical understanding of the horse shoe vortex and its mechanism of loss production in compressor cascades.
The interaction of the passage vortex and the suction side profile boundary layer is influenced. The superposition of both is minimized and the losses developing from this effect are significant lower. The numerical simulation was able to produce results which match the experiments qualitatively. It predicts the same tendencies of loss development. Some local details, which were not accessible in experiments, are discussed.
The modification shows a reduction in losses of 0.5–4 % in dependence of the blade turning or local incidence. This equals a reduction of the isolated secondary losses by 20–40% with respect to the reference profile.
6th European Conference on Turbomachinery – Fluid Dynamics and Thermodynamics March 7 – 11 2004, Lille, France.